Question

Which of the following are true? Select all that apply. The net electric field inside a block of aluminum is zero under all circumstances. The electric field from an external charge cannot penetrate to the center of a block of iron. The net electric field at any location inside a block of copper is zero if the copper block is in equilibrium. In equilibrium, there is no net flow of mobile charged particles inside a conductor. If the net electric field at a particular location inside a piece of metal is not zero, the metal is not in equilibrium.

Answer 1

A conductor in static equilibrium has zero net electric field at all locations inside the surface, so 3 and 5 is true.If the conductor is not in static equilibrium ,then a non zero electric field can exist inside,so 1 is false.It is the net electric field that is zero -external fields can penetrate conductors, but the shift of free charges in the conductor generates an electric field that exactly cancels the external field,so 2 is false.If charges are flowing ,then there is nonzero E field inside the conductor and it is not in static equilibrium ,so 4 is true.

The answer is 3,4,5